APMLE Dermatology and Nail Disorders 3

Question 1

Pitted keratolysis presents with malodorous, punched-out erosions on the plantar surface. Which bacteria is the primary causative agent?

Accepted Answer

Kytococcus sedentarius (Micrococcus sedentarius)

Answer

Kytococcus sedentarius (formerly Micrococcus sedentarius) and Corynebacterium species produce proteases that create the characteristic pitted erosions of pitted keratolysis.

Question 2

A patient presents with a tender, pulsatile, bluish nodule under the nail of the hallux that causes severe pain with cold exposure. What is the most likely diagnosis?

Accepted Answer

Glomus tumor

Answer

A glomus tumor is a benign vascular hamartoma arising from the glomus body that classically presents as a triad of point tenderness, cold sensitivity, and pain — often in the subungual region.

Question 3

Erythrasma affecting the web spaces of the foot is caused by which organism and best treated with which antibiotic?

Accepted Answer

Corynebacterium minutissimum; erythromycin

Answer

Erythrasma is a superficial bacterial infection caused by Corynebacterium minutissimum, characterized by coral-red fluorescence under Wood's lamp and treated with oral erythromycin.

Question 4

Which nail disorder is characterized by excessive lateral curvature of the nail plate that pinches the soft tissue without penetrating it, often causing pain and onycholysis?

Accepted Answer

Pincer nail (involuted nail)

Answer

Pincer nail (trumpet nail) involves transverse overcurvature of the nail plate that compresses the underlying nail bed but does not penetrate the lateral fold as in onychocryptosis.

Question 5

Beau's lines (transverse depressions across the nail plate) occur as a result of:

Accepted Answer

Temporary arrest of nail matrix cell proliferation

Answer

Beau's lines form when systemic illness, severe stress, or nutritional deficiency temporarily halts nail matrix proliferation, creating a transverse groove that grows distally with the nail.

APMLE - American Podiatric Medical Licensing Examination Practice Test

APMLE - American Podiatric Medical Licensing Examination Practice Test

APMLE Dermatology and Nail Disorders 3